Imagine you’re fast asleep and then suddenly awake. You want to move but can’t, as if someone is sitting on your chest. And you can’t even scream! This is sleep paralysis, a creepy but common phenomenon caused by an overlap in REM sleep and waking stages. Ami Angelowicz describes just how pervasive (but harmless) it is and introduces a cast of characters from sleep paralysis around the world.

A lucid dream occurs when the dreamer is aware of the events happening during the dream. Studies suggest that a person can learn to lucid dream by some simple steps outlined in this video. Lucid dreams are strongly associated with REM sleep. REM sleep is more abundant just before being awake. Other ways to practice are to keep a dream journal or practice reality checks like turning on a light switch.